$ { \left[\begin{array}{r}{-2} \\ {-1} \\ {4}\end{array}\right]-\left[\begin{array}{r}{1} \\ {2} \\ {1}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{r}{-2}-{1} \\ {-1}-{2} \\ {4}-{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{r}{-3} \\ {-3} \\ {3}\end{array}\right]}$